Science 10-Electricity & Magnetism Activity 12 Worksheet on Electrical Energy and Power

Transcription

1 Science 10-Electricity & Magnetism Activity 12 Worksheet on Electrical Energy and Power Name Due Date Show Me Hand In 20 Correct and Hand In Again By Note: Information for this worksheet can be found on pages of the textbook. 1. Write the equation for electrical energy using voltage, current and time. (It is just below the middle of page 91 of the text.) Include units! 2. Write the same equation for energy as in question 1, only this time, use the letters V, I and t. 3. A 120 volt light bulb has a current of 0.5 A. running through it for 30 seconds. How much electrical energy does it use in this time? (Include units in your answer!) 4. A 120 volt light bulb has a current of A. running through it for 30 seconds. How much electrical energy does it use in this time? (Include units in your answer!) Activity 12--Worksheet on Electrical Energy and Power Page 1

2 5. A 15 A. saw runs for 2 minutes on a voltage of 120 volts. Calculate the amount of energy used. (Remember to changes min. to seconds!) (Include units in your answer!) 6. Write the equation for power using just current (I) and voltage (V). (This can be found right in the middle of page 92 of the text.) Be sure to state what units everything is in! 7. An electric saw draws 15 A. of current while operating on 120 volts. a) What is the power of the saw? (Include units in your answer!) b) If the saw is operated for 3 minutes, calculate the energy used. (Remember to change minutes to seconds!) (Include units in your answer!) Activity 12--Worksheet on Electrical Energy and Power Page 2

3 8. A walkman draws 200 ma. of current while operating on 3 volts. a) What is the power of the walkman? (Remember to change ma to A!) (Include units in your answer!) b) If the walkman is operated for 3 hours, calculate the energy used. (There are 3600 seconds in one hour.) (Include units in your answer!) 9. An outdoor floodlight has a power rating of 150 watts. a) Calculate the current through the bulb if the voltage is 120 volts. b) Calculate the total energy used by the bulb if it is left on for 10 hours overnight. (1 hour = 3600 seconds) Activity 12--Worksheet on Electrical Energy and Power Page 3

4 10. Joules, Kilojoules and kw h are all units of. 11. Calculate the energy used by a 300 W light bulb that is used to light a yard 9 hours per night for 30 days? Express the answer in kw h. 12. Which has a greater Resistance, a 50 W light bulb or a 100 W light bulb? What would happen to the current if a 50 W light bulb is replaced by a 100 W light bulb?. 13. Calculate the Resistance of an 18 W compact fluorescent light bulb. Assume it is operating at a voltage of 120 V. Answer Ω 14. A 240 V oven element draws 22 A of current. Calculate the energy the element uses if it is cooking a turkey for 3.0 hours. Answer 15. A light bulb consumes 2400 J of energy in 60 s. It is a W light bulb. 16. A projector has a 500 W bulb in it. How much energy does it use when it runs for a 2 hour science double block? Express your answer in kw h. Answer Activity 12--Worksheet on Electrical Energy and Power Page 4

5 17. A 12 V, 6 A motor takes 180 minutes to do a job. A 120 V, 10 A motor takes 5 minutes to do the same job. Which motor uses the least energy and by how much? Answer 18. A 120 V appliance draws 14 A of current. If electricity costs $0.065 kw h, how much does it cost to operate the appliance for 5.5 hours? Answer 19. a) Calculate the current drawn by a 1600 W microwave oven if it is plugged in to a 120 V circuit. b) Will it trip a 15A breaker?. If two microwaves like this are plugged into the same circuit and they are both operating at the same time, would that trip the 15A breaker? 20. How many Joules of energy is used by an 800 W coffee maker operating for ½ an hour? Answer J 21. A 600W fridge is plugged into a 120V circuit. Calculate the Resistance of the fridge. Answer Ω Activity 12--Worksheet on Electrical Energy and Power Page 5

6 22. a) A 340 W television continues to use 6 W even when turned off in order to keep its clock and program settings. Calculate the energy saved in 30 days if the TV unplugged for 12 hours per day and plugged in the rest of the time? Express your answer in kw h. Answer b) If electricity costs $0.065 kw h, how much money would be saved in a month? Answer 23. What is the main advantage of using compact fluorescent light bulbs in a home rather than ordinary incandescent light bulbs? 24. a) A 100 W incandescent light bulb lights a porch for 3 hours a day. How much energy can be saved in a month (30 days) if that 100 W incandescent bulb is replaced with an 18 W compact fluorescent bulb which gives a comparable amount of light? Answer b) If electricity costs $0.065 kw h, how much money would be saved in a month? Activity 12--Worksheet on Electrical Energy and Power Page 6